1. Technical Field
The present disclosure relates to control circuits, and particularly to a control circuit for a fan of a computer.
2. Description of Related Art
Generally, a computer system includes a motherboard with various chips such as central processing units mounted on the motherboard, and a storage device such as a hard disk drive, each of which is known to generate heat when operating in the computer system. Typically, a computer fan is mounted on the motherboard to dissipate the heat timely.
Computer fans ordinarily include 3-pin fans and 4-pin fans. Generally, a 3-pin fan is connected to a motherboard by a 3-pin header mounted on the motherboard, and a 3-pin fan controller provides a voltage signal to the 3-pin fan. A 4-pin fan is connected to a motherboard by a 4-pin fan header mounted on the motherboard, a fourth pin of the 4-pin fan header is used to output a pulse-width modulation (PWM) signal, and a 4-pin fan controller is provided to supply the PWM signal to the 4-pin fan for adjusting a rotary speed of the 4-pin fan. However, the 3-pin fan can be connected to the 4-pin header, while a rotary speed of the 3-pin fan cannot be adjusted because the 3-pin fan does not have the fourth pin to receive the PWM signal.